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From: Peter Zijlstra <peterz@infradead.org>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Russell King <rmk@arm.linux.org.uk>,
	Paul Mundt <lethal@linux-sh.org>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Rik van Riel <riel@redhat.com>, Ingo Molnar <mingo@elte.hu>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	David Miller <davem@davemloft.net>,
	Hugh Dickins <hugh.dickins@tiscali.co.uk>,
	Mel Gorman <mel@csn.ul.ie>, Nick Piggin <npiggin@kernel.dk>,
	Chris Metcalf <cmetcalf@tilera.com>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>
Subject: Re: [RFC][PATCH 4/6] arm, mm: Convert arm to generic tlb
Date: Thu, 17 May 2012 18:44:13 +0200	[thread overview]
Message-ID: <1337273053.4281.50.camel@twins> (raw)
In-Reply-To: <1337272396.4281.48.camel@twins>

On Thu, 2012-05-17 at 18:33 +0200, Peter Zijlstra wrote:
> On Thu, 2012-05-17 at 18:24 +0200, Peter Zijlstra wrote:
> > On Thu, 2012-05-17 at 17:00 +0100, Catalin Marinas wrote:
> > 
> > > BTW, looking at your tlb-unify branch, does tlb_remove_table() call
> > > tlb_flush/tlb_flush_mmu before freeing the tables?  I can only see
> > > tlb_remove_page() doing this. On ARM, even UP, we need the TLB flushing
> > > after clearing the pmd and before freeing the pte page table (and
> > > ideally doing it less often than at every pte_free_tlb() call).
> > 
> > No I don't think it does, so far the only archs using the RCU stuff are
> > ppc,sparc and s390 and none of those needed that (Xen might join them
> > soon though). But I will have to look and consider this more carefully.
> > I 'lost' most of the ppc/sparc/s390 details from memory to say this with
> > any certainty.
> 
> 
> Hmm, no, thinking more that does indeed sounds strange, I'll still have
> to consider it more carefully, but I think you might have found a bug
> there.

So the RCU code can from ppc in commit
267239116987d64850ad2037d8e0f3071dc3b5ce, which has similar behaviour.
Also I suspect the mm_users < 2 test will be incorrect for ARM since
even the one user can be concurrent with your speculation engine.



WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Russell King <rmk@arm.linux.org.uk>,
	Paul Mundt <lethal@linux-sh.org>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Rik van Riel <riel@redhat.com>, Ingo Molnar <mingo@elte.hu>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	David Miller <davem@davemloft.net>,
	Hugh Dickins <hugh.dickins@tiscali.co.uk>,
	Mel Gorman <mel@csn.ul.ie>, Nick Piggin <npiggin@kernel.dk>,
	Chris Metcalf <cmetcalf@tilera.com>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>
Subject: Re: [RFC][PATCH 4/6] arm, mm: Convert arm to generic tlb
Date: Thu, 17 May 2012 18:44:13 +0200	[thread overview]
Message-ID: <1337273053.4281.50.camel@twins> (raw)
In-Reply-To: <1337272396.4281.48.camel@twins>

On Thu, 2012-05-17 at 18:33 +0200, Peter Zijlstra wrote:
> On Thu, 2012-05-17 at 18:24 +0200, Peter Zijlstra wrote:
> > On Thu, 2012-05-17 at 17:00 +0100, Catalin Marinas wrote:
> > 
> > > BTW, looking at your tlb-unify branch, does tlb_remove_table() call
> > > tlb_flush/tlb_flush_mmu before freeing the tables?  I can only see
> > > tlb_remove_page() doing this. On ARM, even UP, we need the TLB flushing
> > > after clearing the pmd and before freeing the pte page table (and
> > > ideally doing it less often than at every pte_free_tlb() call).
> > 
> > No I don't think it does, so far the only archs using the RCU stuff are
> > ppc,sparc and s390 and none of those needed that (Xen might join them
> > soon though). But I will have to look and consider this more carefully.
> > I 'lost' most of the ppc/sparc/s390 details from memory to say this with
> > any certainty.
> 
> 
> Hmm, no, thinking more that does indeed sounds strange, I'll still have
> to consider it more carefully, but I think you might have found a bug
> there.

So the RCU code can from ppc in commit
267239116987d64850ad2037d8e0f3071dc3b5ce, which has similar behaviour.
Also I suspect the mm_users < 2 test will be incorrect for ARM since
even the one user can be concurrent with your speculation engine.


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  reply	other threads:[~2012-05-17 16:44 UTC|newest]

Thread overview: 86+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-02 17:59 [RFC][PATCH 0/6] mm: Unify TLB gather implementations Peter Zijlstra
2011-03-02 17:59 ` Peter Zijlstra
2011-03-02 17:59 ` Peter Zijlstra
2011-03-02 17:59 ` [RFC][PATCH 1/6] mm: Optimize fullmm TLB flushing Peter Zijlstra
2011-03-02 17:59   ` Peter Zijlstra
2011-03-02 17:59   ` Peter Zijlstra
2011-03-02 17:59 ` [RFC][PATCH 2/6] mm: Change flush_tlb_range() to take an mm_struct Peter Zijlstra
2011-03-02 17:59   ` Peter Zijlstra
2011-03-02 17:59   ` Peter Zijlstra
2011-03-02 19:19   ` Linus Torvalds
2011-03-02 19:19     ` Linus Torvalds
2011-03-02 20:58     ` Rik van Riel
2011-03-02 20:58       ` Rik van Riel
2011-03-02 21:40     ` Peter Zijlstra
2011-03-02 21:40       ` Peter Zijlstra
2011-03-02 21:47       ` David Miller
2011-03-02 21:47         ` David Miller
2011-03-03 17:22         ` Chris Metcalf
2011-03-03 17:22           ` Chris Metcalf
2011-03-03 17:22           ` Chris Metcalf
2011-03-03 18:45           ` David Miller
2011-03-03 18:45             ` David Miller
2011-03-03 18:56             ` Chris Metcalf
2011-03-03 18:56               ` Chris Metcalf
2011-03-03 18:56               ` Chris Metcalf
2011-03-10 18:05           ` [PATCH] arch/tile: optimize icache flush Chris Metcalf
2011-03-10 18:05             ` Chris Metcalf
2011-03-10 18:05             ` Chris Metcalf
2011-03-10 23:19             ` Rik van Riel
2011-03-10 23:19               ` Rik van Riel
2011-03-02 17:59 ` [RFC][PATCH 3/6] mm: Provide generic range tracking and flushing Peter Zijlstra
2011-03-02 17:59   ` Peter Zijlstra
2011-03-02 17:59   ` Peter Zijlstra
2011-03-02 17:59 ` [RFC][PATCH 4/6] arm, mm: Convert arm to generic tlb Peter Zijlstra
2011-03-02 17:59   ` Peter Zijlstra
2011-03-02 17:59   ` Peter Zijlstra
2011-03-09 15:16   ` Catalin Marinas
2011-03-09 15:16     ` Catalin Marinas
2011-03-09 15:19     ` Peter Zijlstra
2011-03-09 15:19       ` Peter Zijlstra
2011-03-09 15:36       ` Catalin Marinas
2011-03-09 15:36         ` Catalin Marinas
2011-03-09 15:39         ` Peter Zijlstra
2011-03-09 15:39           ` Peter Zijlstra
2011-03-09 15:48           ` Peter Zijlstra
2011-03-09 15:48             ` Peter Zijlstra
2011-03-09 16:34             ` Catalin Marinas
2011-03-09 16:34               ` Catalin Marinas
2012-05-17  3:05   ` Paul Mundt
2012-05-17  3:05     ` Paul Mundt
2012-05-17  9:30     ` Catalin Marinas
2012-05-17  9:30       ` Catalin Marinas
2012-05-17  9:39       ` Catalin Marinas
2012-05-17  9:39         ` Catalin Marinas
2012-05-17  9:51       ` Russell King
2012-05-17  9:51         ` Russell King
2012-05-17 11:28         ` Peter Zijlstra
2012-05-17 11:28           ` Peter Zijlstra
2012-05-17 12:14           ` Catalin Marinas
2012-05-17 12:14             ` Catalin Marinas
2012-05-17 16:00           ` Catalin Marinas
2012-05-17 16:00             ` Catalin Marinas
2012-05-17 16:24             ` Peter Zijlstra
2012-05-17 16:24               ` Peter Zijlstra
2012-05-17 16:33               ` Peter Zijlstra
2012-05-17 16:33                 ` Peter Zijlstra
2012-05-17 16:44                 ` Peter Zijlstra [this message]
2012-05-17 16:44                   ` Peter Zijlstra
2012-05-17 16:59                   ` Peter Zijlstra
2012-05-17 16:59                     ` Peter Zijlstra
2012-05-17 17:01                   ` Catalin Marinas
2012-05-17 17:01                     ` Catalin Marinas
2012-05-17 17:11                     ` Peter Zijlstra
2012-05-17 17:11                       ` Peter Zijlstra
2012-05-21  7:47               ` Martin Schwidefsky
2012-05-21  7:47                 ` Martin Schwidefsky
2012-05-17 17:22             ` Russell King
2012-05-17 17:22               ` Russell King
2012-05-17 18:31               ` Catalin Marinas
2012-05-17 18:31                 ` Catalin Marinas
2011-03-02 17:59 ` [RFC][PATCH 5/6] ia64, mm: Convert ia64 " Peter Zijlstra
2011-03-02 17:59   ` Peter Zijlstra
2011-03-02 17:59   ` Peter Zijlstra
2011-03-02 17:59 ` [RFC][PATCH 6/6] sh, mm: Convert sh " Peter Zijlstra
2011-03-02 17:59   ` Peter Zijlstra
2011-03-02 17:59   ` Peter Zijlstra

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